Piston assembly



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NTOR

NDLLR c. SCHINDLER PISTON ASSEMBLY I Filed March 3, 1952 Deb. 8, 1936.

ATTORNEY.

I ll ll Ii I. I I I INV EARL. SUI-II VZA/W Patented Dec. 8, 1936 PATENT o Fica PISTON ASSEMBLY Carl Schindler, Wauwatosa, Wis, assignor to The Oilgear Company, Milwaukee, Wis, a corporation of Wisconsin Application March 3, 1932, Serial No. 596,479 4 Claims. (01. 103-161) This invention relates'to pistons for hydraulic pumps and motors.

The pump or motor to which the invention is particularly adapted is of the type which is pro- 5 vided with a central valve or pintle having intake and discharge ports and passageways, a cylinder barrel rotating on the pintle and provided with radial cylinders having ports at the inner ends thereof to register with the intake and dicharge 1o ports alternately as the cylinder barrel rotates, and a driver rotating in unison with the cylinder andconnected to the pistons to reciprocate the same whenever its axis of rotation is eccentric to the axis of the pintle, such as the pump disclosed 15 in Patent No. 1,619,200 issued March 1, 1927 to Walter Ferris. i

The pistons of such pumps are ordinarily provided with a central bore or socket having a push pin arranged therein with its inner end in engage- 20 ment with the inner end of the socket and its outer end connected'to a crosshead which is engaged by the driver.

The entire force required to expel liquid from the cylinder is-thus carried by the relatively small 25 bearing surface between the end of the push pin and the end of the socket, and this surface is unlubricated.

The pintle is ordinarily supported at one end only and, when the pump isdelivering liquid at 3 sufliciently high pressure, the pintle is deflected and causes the cylinders to revolve in a plane which is displaced from the normal plane of revolutionand at an angle thereto. Displacement of the plane of revolution causes the unlubri- 35 cated bearing surfaces on the push pin and the piston to move relatively to each other.

This invention has an object to provide a piston assembly having increased bearing surfaces through which pumping forces are transmitted 40 from the crosshead to the liquid.

Another object is to lubricate the bearing surfaces through which pumping forces are transmitted from the crosshead to the liquid.

Another object is to provide a piston. assembly "45 in which a part of the pumping force is transmitted to the liquid independent of the piston.

According to the invention as ordinarily applied and embodied in practice, a substantially tubular piston is provided with an open concave seat, a 50 crosshead carries an annular. convex seat which is fitted in the concave seat, and a spring holds the convex seat in engagement with the concave seat.

The accompanying drawing illustrates an em 55 bodiment of the invention and shows the same incorporated in a pump rotor of the type disclosed in Patent No. 1,619,200.

The views in the drawing are as follows:

Fig. 1 is an end view of the rotor, the cylinders and one of the pistons being shown in central section.

Fig. 2 is a section taken on the line 2-.-2 of Fig. 1.

The pump rotor is provided with a cylinder barrel l which is' journaled upon a central shaft or pintle 2 and rotated thereon by a driver 3 which is driven from an external source of power and supported independently of the pintle with its axis of rotation eccentric to the axis of the pintle.

The pintle is ordinarily supported at one end only by mechanism not shown and is provided with an intake port 4 and a discharge port 5 which are arranged diametrically opposite each other and communicate, respectively, with an intake passage 6 and a discharge passage 1 formed in the pintle longitudinally thereof.

The cylinder barrel is provided with five radial cylinders 8 each of which has a port 9 in the inner endthereof to register with the ports 4 and 5 alternately as the cylinder barrel rotates.

Each cylinder has a piston Ill fitted therein and connected by a piston pin II to a crosshead l2 by means of which the piston is reciprocated in the cylinder.

The cylinder barrel isarranged'within an annular flange l3 which is formed upon the driver 3 and provided upon its outer periphery with five tangential faces I! each of which is arranged at the end of a cylinder 8. p

The flange I3 has a slot l5 formed therein intermediate the ends of each face H to permit the passage therethrough of the piston pin it, and each slotordinarily has suflicient length to permil; the piston Hi to move'therein longitudinally 40 of the face.

The driver is provided upon its outer periphery opposite each face II with a segmentalflange [6 which has a bearing plate ll arranged upon its inner face parallel to the face I and secured in 5 position by a screw I8.

The inner face of each crosshead engages a face l4 and is held in engagement therewith by an antifriction bearing llwhich is arranged between the outer face of the crosshead and the inner face of the bearingplate II, the bearing l9 being ordinarilyretained in position between the crosshead andthe bearing plate by a pin 20 carried by the crosshead and extending into a slot 2| formed in the race of the bearing l9. I

When the driver is rotated in the direction of the arrow, the cylinder barrel is rotated also and the pistons in the lower half of the cylinder barrel in respect to Fig. 1 are drawn outward by the crosshead bearing upon the faces l4 and the cylinders in the upper half of the cylinder barrel are forced inward by the thrust of the bearing plate acting through the anti-friction bearing.

The outward moving pistons draw liquid into their cylinders through the passage 6 and the ports 4 and 9, and the inward moving pistons expel liquid from their cylinders through the ports 8 and 5 and the passage 1.

The entire force exerted by the driver upon the pistons to expel liquid from the pump is carried by its pintle and, when the liquid meets a high resistance, this force is sufficient to bend the pintle and thereby deflect the cylinder barrel from its normal plane of rotation and cause relative movement between the push pin and the piston. I r

The pump rotor shown and thus far described is substantially the same as the rotor disclosed in Patent No. 1,619,200 with the exception of the piston assembly in which the invention is embodied and which will now be described.

The piston I0 is substantially tubular and provided at its outer end with an annular concave seat 22 through which the piston pin ll extends.

The seat 22 is engaged by a complementary convex seat 23 which closes the outer end of the piston and is ordinarily in the form of a truncated spherical segment rigidly secured to the crosshead i 2 as by being formed integral therewith. The piston pin ll extends from the convex seat 23 through the concave seat 22 into the piston and is ordinarily formed integral with the seat 23 and the crosshead l2.

The convex seat 23 is held in engagement with the concave seat 22- by a helical compression spring 24 which encircles the pin II and has one of its ends abutting the underside of the seat 22 and its other end abutting a nut 25 threaded upon the inner end of the pin H.

The nut 25 is fastened in adjusted position upon the pin l I by a pin 26 which extends therethrough and through the pin II, the piston [0 being provided at its inner end with opposed notches 21 to allow the pin 26 to be inserted and its ends upset to hold it in position.

The spring 24 holds the convex seat 23 against the concave seat 22 with suflicient force to maintain therebetween an oil tight joint which is lubricated by a film of oil supplied thereto from the high pressure oil within the piston when it is expelling oil from the cylinder.

When pump pressure increases sufllciently to cause deflection of the cylinders from their normal plane of revolution, the seats 22 and 23 may move relatively to each other without undue friction as the same are efflciently lubricated.

The force exerted by the. driver in expelling liquid from the cylinder is transmitted in part through seat 23 and the piston pin ll direct to the liquid in the cylinder and in part through the seat 22 and the tubular piston. Consequently, the piston carries only a fraction of the pumping forces which had to be carried entirely by the piston of the prior pump.

The invention herein set forth is susceptible of various modifications and adaptations'within the scope of the appended claims.

The invention is hereby claimed as follows:

1. The combination, with a pump having a radial cylinder revolvable within a circle, a thrust member rotatable upon an axis offset from the axis of said circle, and a reaction surface arranged upon said thrust member at a tangent to said circle, of a piston arranged in said cylinder and having a passage of substantial diameter extending therethrough, a concave seat arranged around said passage, a crosshead bearing against said reaction surface for transmitting pumping forces from said thrust member to the liquid in said cylinder, a piston pin rigidly secured to said crosshead at right angles thereto and extending through said seat and into said passage, and a convex seat rigidly secured to said piston pin and engaging said concave seat to thereby close said passage and transmit a substantial part of said pumping forces direct and through said pin to the liquid in said cylinder and to transmit another part of said pumping forces through said piston.

2. The combination, with a pump having a radial cylinder revolvable within a circle, a thrust member rotatable upon an axis offset from the axis of said circle, and a reaction surface arranged upon said thrust member at a tangent to said circle, of a piston arranged in said cylinder and having a passage of substantial diameter extending therethrough, -a concave seat arranged around said passage, 9. crosshead bearing against said reaction surface for transmitting pumping forces from said thrust member to the liquid in said cylinder, a piston pin rigidly secured to said crosshead at right angles thereto and extending through said seat and into said passage, and a convex seat rigidly secured to said piston pin and bearing upon said crosshead and engaging said concave seat to thereby close said passage and transmit a substantial part of said pumping forces direct and through said pin to the liquid in said cylinder and to transmit another part of said pumping forces through said piston.

3. The combination, with a pump having a radial cylinder revolvable within a circle, a thrust member rotatable upon an axis offset from the axis of said circle, and a reaction surface arranged upon said thrust member at a tangent to said circle, of a piston arranged in said cylinder and having a passage of substantial diameter extending therethrough, a concave seat arranged around said passage, a crosshead bearing against said reaction surface for transmitting pumping forces from said thrust member to the liquid in said cylinder, a piston pin rigidly secured to said crosshead at right angles thereto and extending through said seat and into said passage, a convex seat rigidly secured to said piston pin and engaging said concave seat to thereby close said passage and transmit a substantial part of said pumping forces direct and through said pin to the liquid in said cylinder and to transmit another part of said pumping forces through said piston,

an abutment carried by said pin, an abutment carried by said piston, and a spring arranged around said pin in'engagement with said abutments for keeping said seats in contact with each other.

4. The combination, with a pump having a radial cylinder revolvable within a circle, a thrust member rotatable upon an axis offset from the axis of said circle, and a reaction surface arranged upon said thrust member at a tangent to said circle, of a piston arranged in said cylinder and having a passage of substantial diameter extending therethrough, a concave seat arranged around said passage, a crosshead bearing against said reaction surface for transmitting pumping aaaaaet forces from said thrust member: to the liquid in said cylinder, a piston pin rigidly secured to said crosshead at right angles thereto and extending through said seat and into-said passage, anonvex seat rigidly secured to said piston pinand bearing upon said crosshead and engaging said concave'seat to thereby close said passage and transmit a substantial part of said numbin forces direct and through said pin to the liquid in said cylinder and to transmit another part of said pumping forces through said piston, an abutment carried by said pin, an abutment carried by said piston, and a spring arranged around s pin in engagement with said abutments for i ing said seats in contact with each other.

CARL SCHINDLER. 

